Use last previous assignment for comprehension-escape

[asottile]

Resolves #2130

[asottile]

I tried very hard to write a test for

[x for x in range(3)]
[x for x in range(3)]

but I could not get my test to fail :/

Here's what I had:

+        node = astroid.extract_node('''
+        [i for i in range(3)]
+        [i for i in range(3)]
+        ''')
+        with self.assertNoMessages():
+            self.walk(node)

but it was passing :'(

either way, my patch seems to fix that one as well (#2106)

[coveralls]

Coverage increased (+0.002%) to 89.989% when pulling 9bc2f51 on asottile:newly_introduced_assign into 15c10e8 on PyCQA:master.

[coveralls]

Coverage increased (+0.002%) to 89.989% when pulling 9bc2f51 on asottile:newly_introduced_assign into 15c10e8 on PyCQA:master.

[coveralls]

Coverage increased (+0.002%) to 89.989% when pulling 9bc2f51 on asottile:newly_introduced_assign into 15c10e8 on PyCQA:master.

[coveralls]

Coverage increased (+0.002%) to 89.989% when pulling 9bc2f51 on asottile:newly_introduced_assign into 15c10e8 on PyCQA:master.

[PCManticore]

Thank you for the fix @asottile !